When is a comeback not a comeback? When it’s Alexander Armstrong and Ben Miller. Seven years after their last Channel 4 series together, the talented twosome have returned, on BBC One this time, with an armoury of new characters. Farewell bottom-baring Nude Practice and bewigged Scando-rockers Strijka, hello the dentist who talks filthy during fillings and the divorced dad who is too honest with his son. “

It’s not a comeback because we never really made it in the first place,” chuckles Armstrong, 37, over lunch. It would make good copy to say they split because of mutual loathing, but they have been firm friends since they met after Cambridge. Their wives are even now discussing nanny-sharing. Miller, 41, always thought they would reunite: “When we started together we hoped we’d do it all our lives. The only surprise was that it took another six years.”

The trouble was that they were too busy. Miller carved out his name in the sitcom The Worst Week of My Life and umpteen other roles requiring a more handsome version of Rob Brydon, including the new movie Razzle Dazzle, out this month. Armstrong has been preoccupied with the domestic comedy Life Begins, those actually-quite-funny Pimms ads and countless panel games, most notably as supersub on Have I Got News for You: “I feel like that Geordie AC/DC obsessive who got the call to take over when Bon Scott died.”

The chums did not actually plan this reunion, admits Armstrong as he tucks into his salad: “It was put to us; whereas in the past we’d been clamouring at broadcasters’ gates. Initially we were lukewarm, but then we did a gig and thought it would be really fun.” With other writers also contributing was it hard work? “Just as we were finishing we had a glut of ideas and stayed in the office until 6.30pm. Oops gave the game away there... ”

In many respects they have picked up where they left off, with more costume drama spoofs and rudeness. So have A&M gone mainstream or has the BBC, postLittle Britain, gone more alternative? Miller says both: “If C4 was Cambridge and BBC One was London, then BBC One has moved to Hitchin.” Armstrong – Xander to friends – has never got over not being on the Beeb in the first place: “We always felt we were such obvious BBC candidates; that’s why they rejected us. It was a self-purging period and to be a middle-class white male was wrong. At one meeting they actually asked us, ‘Do you know a black girl?’ ”

Armstrong adds that they’ve no qualms about going for a Morecambe-and-Wise following: “BBC One feels right. Ricky Gervais said that he didn’t want to do BBC One because that was making comedy for an audience that didn’t have a sense of humour. I couldn’t disagree more.”

The biggest change is having The League of Gentlemen’s Jeremy Dyson as script editor. He has clearly injected some oomph, penning sketches and pointing others in the right direction, explains Miller: “We were huge fans of Jeremy.” Dyson’s dickie-bowed influence can be seen in the number of send-ups of old monochrome movies and Fifties television. Take Brabbins and Fyffe, the filthy reimagining of Flanders and Swann. “Jeremy said, ‘You remind me of a double act from the Forties and Fifties.’ I think we are throwbacks.” Armstrong agrees: “Whenever I do an interview on Radio 2 Al Murray e-mails me and says it’s like listening to radio from the Fifties.”

Miller is particularly fond of “the chav pilots”, moustachioed Second World War fly-boys talking Nough- ties street slang: “That came about when we were thinking what if teenagers today were the teenagers of the Battle of Britain. The result was this brilliant mix of two random ideas that suddenly tessellate.”

If things take off, the next challenge will be fitting another series around their solo commitments. Armstrong has a new comedy-drama, Mutual Friends, with Keeley Hawes; Miller is involved in an intriguing ITV project. Echo Beach/Moving Wallpaper by Tony Jordan, who made Life on Mars.“Half the show is a serious soap opera, starring Martine McCutcheon and Jason Donovan, and half is a behind-the-scenes comedy in which I play the producer. It’s a little like Extras but also draws on reality TV. Very zeitgeisty.” However many solo gigs they land, though, A&M are determined to reconvene. “It’s about control,” says Armstrong. “That was a huge reason for wanting to work together. It’s always better than being a small cog. And if it is a disaster, at least we can say it’s our disaster.”

The Armstrong & Miller Show, Friday, BBC One, 9.30pm; N. Ireland 12.05am

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